This is an ongoing list detailing all films available on the OFFICIAL YouTube Movies channel under 'Free-to-watch'. I refer to the official playlist as reference.
To be updated daily.

Don't worry, Letterboxd team, they're completely legal. Please don't take this down like you did on 27 July 2020 for Full movies on Youtube!

Note: Check the links in the Notes. Use a VPN if you're outside U.S. and can't load the films!

(Yeah, I know, most of these are awful, but sort by rating/popularity and you'll likely see the best ones)

NOT ON LETTERBOXD:
Led Zeppelin: Dazed and Confused (2012) Amazon
Illustrated: A Vans BMX Video (2016) Amazon
One Direction: The Inside Story (2014) IMDb
Fun with Slime: Part 1 (2019) Amazon
Fun with Slime: Part 3 (2019) Amazon
Ernest's Greatest Hits Volume 1 (1986) Amazon
RWBY: Volume 1 (2013) IMDb
RWBY: Volume 2 (2014) IMDb
RWBY: Volume 3 (2016) IMDb
RWBY: Volume 4 (2017) IMDb
RWBY: Volume 5 (2018) IMDb
Beyoncé: Fierce and Fabulous (2014) Amazon
The Last 24 Hours: Amy Winehouse (2019) Amazon
Nostradamus: Future Tense (2020) IMDb
The Diana Story: Part I: The Young Princess (2017) Amazon
The Diana Story: Part II: Broken Hearts (2017) Amazon
Diana: The Royal Truth (2017) Amazon
The Great Outdoors: Eleven (2018) IMDb
Elvis & The Memphis Mafia (2018) IMDb
509 Films: Volume 11 (2016) 509
Lil Wayne: Rap Sheet (2013) Amazon

NEW ARRIVALS:
Love Won't Let Me Wait (2016), Answer This! (2011), Iceman (2014), Missing 411: The Hunted (2019), Paper Angels (2014), Raging Bull (1980), Stanley & iris (1990), War of the Buttons (1994), 10 Years (2011), Battle of Kings: Bannockburn (2014), Evil Alien Conquerors (2003), The Jackie Robinson Story (1950), Abandoned (2010), Agent Cody Banks 2: Destination London (2004), Caught in the Crossfire (2010), Impasse (1969), Ladrones (2015), The Mermaid: Lake of the Dead (2018), Monumental: Skiing Our National Parks (2016), The Cassandra Crossing (1976), Badges of Fury (2013), Iceman: The Time Traveler (2018), Imaginary Crimes (1994), Itsy Bitsy (2019), Valentine (2017), 12 Angry Men (1997), Adios Sabata (1970), Billy Two Hats (1974), The Charge of the Light Brigade (1968), Convict Cowboy (1995), Cooley High (1975), Dillinger (1945), Evelyn (2002), Juggernaut (1974), King Solomon's Mines (1985), Mission of the Shark: The Saga of the U.S.S. Indianapolis (1991), Moby Dick (1956), Mountain (2017), Night of the Comet (1984), Return of Sabata (1971), Support Your Local Sheriff! (1969), The Adventures of Hercules (1985), The Island of Dr. Moreau (1977), The Return of a Man Called Horse (1976), The Spikes Gang (1974), A la mala (2015), Beyond a Reasonable Doubt (2009), Masters of the Universe (1987), Shaquille O’Neal Presents: All Star Comedy Jam: Live From Sin City (2016), Toonstone (2015), In Enemy Hands (2004), Some Like It Hot (1959), Mr. Church (2016), New in Town (2009), Post Grad (2009), Reasonable Doubt (2014), The Love Punch (2013), Barefoot (2014), From Within (2008), Mystic Pizza (1988), Butterfly on a Wheel (2007), The Quiet Ones (2014), A Bridge Too Far (1977), American Terrorist (2020), Antwone Fisher (2002), Dances with Wolves (1990), Free Birds (2013), Little Italy (2018), Out of Time (2003), Patriots Day (2016), Rain Man (1988), RoboCop 3 (1993), School Dance (2014)

NO LONGER ON PLAYLIST BUT STILL AVAILABLE (incomplete list):
American Terrorist, Borrowed Hearts (1997), Bridge of Dragons (1999), Inherit the Wind (1999), Salt & Pepper (1968), Savage Dog (2017), The 39 Steps (1935), Transpecos (2016), Back in Time (2015), Barabbas (1961), Beyond Sherwood Forest (2009), Interview with a Hitman (2012), Kung Fu Yoga (2017), Shattered (1991), The Pride of the Yankees (1942), Concrete Canyons (2010), Drug War (2012), Drug War (2012), Ernest Goes to School (1994), Joseph and Mary (2017), Merry in-Laws (2012), Shade (2003), The Bone Snatcher (2003), The Dirty Dozen: The Deadly Mission (1987), The Family Fang (2015), The Monkey King (2014), The U.S. vs. John Lennon (2006), The Wrath of Vajra (2013), Ephraim's Rescue (2013), Hans Christian Andersen (1952), Mirage Men (2013), Princess Caraboo (1994), The Winslow Boy (1999), The Family Fang (2015), Abandoned (2015), Digimon Adventure tri. Part 4: Loss (2017), Finding Noah (2015), Frailty (2001), Kenny Rogers as The Gambler (1980), Scorched (2003), Swallows and Amazons (2016), Task Force: Caviar (2000), The Octagon (1980), The Secret Life of Walter Mitty (1947), Wu Dang (2012), If I Were You (2012), Kung Fu Jungle (2014), New World (2013), Prodigy (2017), Sahara (1983), The Wave (2015), A Kind of Murder (2016), Black Christmas (1974), Christmas for a Dollar (2013), Christmas on Salvation Street (2015), Dream a Little Dream (1989), Hard Cash (2002), Journey to the Christmas Star (2012), King of California (2007), Knuckleball! (2012), My Other Mother (2014), Nosferatu the Vampyre (1979), Special ID (2013), Suburban Gothic (2014), The Assassins (2012), The Fighting Preacher (2019), The Mighty Quinn (1989), The Tillman Story (2010), The Truth About Emanuel (2013), Thin Ice (2011), Thsi Beautiful Fantastic (2016), A Girl Like Her (2015), A Royal Night Out (2015), Love Stinks (1999), Men with Brooms (2002), Rocky Marciano (1999), Stranded (2001), The Dawn (2020), The Thieves (2012), Upside Down (2012), A Frosty Affair (2015), Affliction (1997), Any Day (2015), Railroad Tigers (2016), The Timber (2015), The Best of Times (1986), Christmas Crush (2012), Love Trap (2005), The Gate (1987), Island of Fire (1990), American Pastoral (2016), Away from Her (2006), FIshing Naked (2015), Sparks (2013), The Birdcage (1996), The Proud Rebel (1958), Warriors of Heaven and Earth (2003), Alex & the List (2018), Barquero (1970), Christmas Coupon (2019), Diary of a Tired Black Man (2009), G.B.F. (2013), Gift of the Magi (2010), Plato's Run (1997), Red Lights (2012), Southern Comfort (1981), Stock Option (2015), The Adventurers (2017), The Lords of Flatbush (1974), 1911 (2011), Windfall (2002), Faces in the Crowd (2011), Food, Inc. (2008), Lil Wayne: Bling (2018), The Dinner (2017), WHat We Did on Our Holiday (2014), The 51st State (2001), A War (2015), Almost Friends (2016), Ambush Bay (1966), Apartment 1303 3D (2012), Avenging Angelo (2002), Bernie (2011), Chocolate (2008), City of Fear (2000), Country Crush (2016), Danika (2006), Dudes & Dragons (2015), H8RZ (2015), I'll Follow You Down (2013), Kung Fu Jungle (2014), Lavalantula (2015), Marilyn Hotchkiss’ Ballroom Dancing & Charm School (2005), Moto 6: The Movie (2014), Mountain Patrol (2004), Nancy (2018), Painted Skin: The Resurrection (2012), Phase IV (2002), Rapid Exchange (2003), SLAY: The Axell Hodges Story (2017), Shark Attack (1999), Shark in Venice (2008), Synchronicity (2015), The Atticus Institute (2015), The Fitzgerald Family CHristmas (2012), The Hot Flashes (2013), The Visit: An Alien Encounter (2015), Top of the World (1998), Very Good Girls (2013), A Company Man (2012), A Christmas Tail (2014), Full of Grace (2015), Slap Her... She's French (2002), Slightly Single in L.A. (2013), Tangerines (2013), The Dirty Dozen: The Fatal Mission (1988), All Things Must Pass (2015), CIty of Joy (1992), Ernest in the Army (1998), Mythica: The Darkspore (2015), Santa Girl (2019), This Must Be the Place (2011), American Ninja 3: Blood Hunt (1989), Bob the Butler (2005), Everything or Nothing (2012), Happy Christmas (2014), More Dead than Alive (1969), Saving Christmas (2014), The King's Choice (2016), We'll Never Have Paris (2014), Dancer, Texas Pop.81 (1998), Mythica: The Necromancer (2015), Audrey Rose (1977), Going Overboard (1989), Nine (2009), Killing Hunther (2017), Stay Tuned (1992), The Last Five Years (2014), Just Let Go (2015), Elmer Gantry (1960), Elfette Saves Christmas (2019), Crooked Arrows, Attack (1956), Collision (2013), Living on One Dollar (2013), 8 Assassins (2014), All About the Money (2017), Jack and Jill vs. the World (2008), Unexpected (2015), Digimon Adventure tri. Part 3: Confession (2016), Glass Trap (2005), Infinity (1996), The First Great Train Robbery (1978), Bakery in Brooklyn (2016), Buried Treasure (2001), King Naresuan 1 (2007), A Perfect 14 (2018), Count Yorga, Vampire (1970), The Mod Squad (1999), The Wondeful Country (1969), 4th Man Out (2015), Commitment (2013), The Confirmation (2016), Cardboard Boxer (2016), Freeheld (2015), First Born (2007), Chasers (1994), Ernest Rides Again (1993), Bob Marley: Roots of the Man (2018), Green Dragon (2001), Larry Gaye: Renegade Male Flight Attendant (2015), Miss Conception (2008), Making Babies (2018), Straight A's (2013), Who Gets the Dog? (2016), The Final Cut (2004), Vampire's Kiss (1988), Copying Beethoven (2006), Prince Avalanche (2013), Marilyn Monroe Declassified (2015), Ned Kelly (1970), Parkland (2013), The Almost Perfect Bank Robbery (1999), The Jade Pendant (2017), Rosencrantz & Guildenstern Are Dead (1990), The Christmas Candle (2013), The Cokeville Miracle (2015), The Brass Teapot (2012), Z for Zachariah (2015), Another Mother's Son (2017), Atlas Shrugged: Part II (2012), The Return of Swamp Thing (1989), Touched (2005), Saint Ralph (2004), The Brothers Bloom (2008), Between Strangers (2002), Humor Me (2017), Mr. Fix It (2006), Shadow of Fear (2004), Wind (1992), Brick Lane (2007), Oklahoma Crude (1973), That Sugar Film (2014), Trading Mom (1994), All We Had (2016), Retrograde (2004), Burning Bright (2010), Fun with Dick and Jane (1977), Robot & Frank (2012), Sarah's Key (2010), The Longest Week (2014), The Nugget (2002), The Perfect Family (2011), Living It Up (2000), Sky Line (2015), Sunshine State (2002), The Oranges (2011), Mao's Last Dancer (2009), A Street Cat Named Bob (2016), Kon-Tiki (2012), The Concert (2009), Hanover Street (1979), The Bandit Hound (2016), Keep the Aspidistra Flying (1997), The Bad Mother’s Handbook (2007), Shoot First: A Cop’s Vengeance (1991), Parts Per Billion (2014), The Mimic (2017), The Ticket (2016), Big Fish & Begonia (2016), Comeback Season (2006), Absolutely Anything (2015), King Naresuan 2 (2007), Hey Vern, Win $10,000…Or Just Count On Having Fun! (1987), Christmas in Hollywood (2014), Bad Ass (2012), Bottle Shock (2008), Cymbeline (2014), Danny Deckchair (2003), Why I Wore Lipstick to My Mastectomy (2006), All Forgotten (2001), Man Up (2015), Monster Island (2004), Priceless (2006), Remember the Daze (2007), The Last Keepers (2013), The Odyssey (2016), The Challenger Disaster (2019), Charm (2013), Bad Parents (2012), Another Harvest Moon (2010), Beauty (1998), Nobel Son (2007), Lobster War (2018), Beauty (1998), Dr. Otto And The Riddle Of The Gloom Beam (1986), From Nowhere (2016), Newlyweds (2011), The Russian Five (2018), Thank God It's Friday (1978), Hairbrained (2013), Passion Fish (1992), Lost and Found in Armenia (2012), Welcome to Happiness (2015), This Changes Everything (2015), The Drew: No Excuse, Just Produce (2016), Shoot First: A Cop's Vengeance (1991), Fear X (2003), Death of a Salesman (1985), The Competition (2018), The Wolfpack (2015), Food Stamped (2010), In Football We Trust (2015), Apple of My Eye (2017), Union Bound (2019), 10E (2019), Looking For Lola (1997), Blame (2017), The Bet (2016), Husband For Hire (2008), !0E (2019), Dirty (2005), The Bet (2016), Mazes and Monsters (1982), Broken English (2007), Local Boys (2002), Love & Saucers (2017), The Great Invisible (2014), When Did You Last See Your Father? (2007), Despite the Falling Snow (2016), Kingdom of Shadows (2015), Little Men (2016), Masterminds (1997), The Birdcatcher (2019), The Sapphires (2012), Misconception (2014), Dudes & Dragons (2015), Love & Saucers (2017), Police Story 2013 (2013), How Long Will I Love U (2018), The Boy Downstairs (2017), The Open Road (2009), Take (2008), Dead Snow 2: Red vs. Dead (2014), Ass Backwards (2013), Britney Spears: Workin' It (2014), Red Knot (2014), Jurassic City (2015), 91 Bullets in a Minute (2014), The Boy Downstairs (2017), Paper Heart (2009), 2:Hrs (2018), The Road Within (2014), Who Killed the Electric Car? (2006), Forever Strong (2008), Eloise (2017), Austin Found (2017), Dangerous Liaisons (2012), Song One (2014), Without Evidence (1995), Wolf Warrior (2015), Every Little Step (2008), The Little Traitor (2009), The Quiet (2005), Zeitgeist: Addendum (2008), The Boy Downstairs (2017), All the Queen's Horses (2017), Paradox (2017), Meet the Patels (2015), The Last 24 Hours: Jimi Hendrix (2019), Song for Marion (2012), Pretty Ugly People (2009), 50 Cent: Rap Star (2016), Miley Cyrus: Twerk It (2014), Sunshine Superman (2015), The Era of Vampires (2003), Shadow Dancer (2012), Selena Gomez: Living the Dream (2014), Slime Time (2019), Justin Timberlake: Suited Up (2014), Gang of Roses (2003), A Stand Up Guy (2016), Iris (2014), Message Man (2018), Newman (2015), The Extra Man (2010), Dolly Parton: Queen of Country (2015), Eminem: Behind the Lyrics (2013), Finding Altamira (2016), Girls vs Gangsters (2018), Carrie Underwood: Country Idol (2014), The Beauty Inside (2015), Charlie & Boots (2009), Tag (2015), The Taking of Tiger Mountain (2014), Lamb (2015)

WHAT JUST LEFT:
The Alamo: Thirteen Days to Glory (1987), Stargate Origins: Catherine (2018), 12 Angry Men (1957), 1982 (2013), Duck, You Sucker (1971), A Most Wanted Man (2014), A View to a Kill (1985), Alien from L.A. (1988), Backtrack (2015), Bandits (2001), Barbershop 2: Back in Business (2004), Bloodsport (1988), Cattle Annie and Little Britches (1981), Cheech & Chong’s The Corsican Brothers (1984), Child's Play (1988), Citizenfour (2014), Coriolanus (2011), Dark Tide (2012), Diamonds Are Forever (1971), Dr. No (1962), Dragon Blade (2015), Earth Girls Are Easy (1988), Erik the Viking (1989), Fair Game (2010), Fargo (1996), For Your Eyes Only (1981), From Russia with Love (1963), Gimme Shelter (2013), GoldenEye (1995), Goldfinger (1964), Good Boy! (2003), Good Hair (2009), Hang 'em High (1968), Hannibal (2001), Into the Blue (2005), Jessabelle (2014), Khartoum (1966), Legendary: Tomb of the Dragon (2013), Licence to Kill (1989), Live and Let Die (1973), Spooks: The Greater Good (2015), Mannequin Two: On the Move (1991), Meatballs (1979), Moonraker (1979), Mr. Mom (1983), Never Say Never Again (1983), Nothing Like the Holidays (2008), Octopussy (1983), On Her Majesty's Secret Service (1969), Overboard (1987), Paths of Glory (1957), Planet Hulk (2010), Precious Cargo (2016), Return to Me (2000), Road House (1989), Ronin (1998), Stigmata (1999), Teen Wolf (1985), Teen Wolf Too (1987), The Amityville Horror (2005), The Arrival (1996), The Cutting Edge: Chasing the Dream (2008), The Cutting Edge: Going for the Gold (2006), The Forger (2014), The Living Daylights (1987), The Man with the Golden Gun (1974), The Miracle Worker (1962), The New Daughter (2009), The Silence of the Lambs (1991), The Spy Who Loved Me (1977), The Three Musketeers (2011), The World Is Not Enough (1999), Thunderball (1965), Tomorrow Never Dies (1997), Tracers (2015), Traitor (2008), Vehicle 19 (2013), Wanda Nevada (1979), WarGames (1983), Yellowbeard (1983), You Only Live Twice (1967)

Omission issues documented in YouTube Forums.

Workflow for updating and maintenance (which will be reduced if only YouTube adds the feature to sort videos in playlists alphabetically):
1) Copy link of 'Free to watch' playlist.
2) Backup here. If not working, do it here.
3) Copy all titles from Excel/text file.
4) Alphabetise all the titles in the list.
5) Compare or diff the current and previous lists, and update this Letterboxd list accordingly.
6) Repeat steps 1 to 5 daily.